The Insulated Gate Bipolar Transistor (IGBT) device is a three terminal device including an N-channel Metal Oxide Semiconductor Field Effect Transistor (MOSFET) and a PNP bipolar transistor connected in a Darlington configuration. Such a Darlington configuration enables the IGBT device to have MOSFET input characteristics and bipolar output characteristics. The IGBT device is a voltage-driven bipolar device. The voltage-driven IGBT device exhibits exceptional features such as simple gate-drive characteristics of MOSFETs at the gate-emitter terminals and a high-current and low-saturation-voltage capability of Bipolar Junction Transistors (BJTs) at the collector-emitter terminals.
The IGBT device includes three terminals, namely an emitter, a gate and a collector. In operation, when a gate voltage surpasses a turn-on threshold voltage of the IGBT device, the IGBT device is turned on. On the other hand, the IGBT device is turned off if the gate voltage goes down below the turn-on threshold voltage.
The IGBT device is a unidirectional device. More particularly, the IGBT device can only allow the current to flow in a direction from the collector to the emitter of the IGBT device. In comparison, MOSFET devices have bi-directional current switching capabilities.
IGBT devices are widely used in high power applications, such as inverters for three-phase drives, high voltage converters, uninterruptible power supplies and switching mode power supplies. IGBT devices have a low on-state voltage drop, but their switching speeds are slow. MOSFETs may have higher switching speeds, but high-voltage and high-current MOSFET devices are expensive and hard to achieve.
It would be desirable to have an integrated device for use in high voltage applications (e.g., 600 volts) exhibiting good behaviors such as higher breakdown voltage, lower on-resistance and lower switching losses.